Centrifugal drier for textile fibers



July l, 1941. A. cAsAGRANDE CENTRIFUGAL DRIER FOR TEXTILE FIBERS Filed April 4. 1938 Patented July 1, 1941 CENTRIFUGAL DRIER FOR TEXTILE FIBERS Aldo Casagrande, Milan, Italy Application April 4, 1938, Serial No. 200,035 In Italy April 15, 1937 4 Claims.

'I'he present invention relates to apparatus for dehydrating textile bers.

Centrifugators operating continuously and automatically are known and have been employed in various industries. They have a rotating basket of a truncated-conical shape, in the inside of which revolves in the same direction, but with a certain step in velocity, a trunco-conical multiple screw, whose function is to carry and guide the materials to be submitted to centrifugal action for extracting from them the liquids they contain and by dropping said materials along the spirals of said screw they move towards the bottom of the basket land thence discharge as dried material.

Such machines have found several uses in the treatment, of solid materials, more or less subdivided in crystals and grains, but due to their features and design they are not suited for the treatment of natural or artificial textile fibers, because the materials obstruct either that part of the rotor where they are introduced in the machine or the part from which the dried material is discharged from the machine.

According to the present invention a machine is provided in which the angle of the conical walls of the basket to its rotation axis is made steeper than the friction angle of the various textile fibers to be dried out on the basket Walls. This angle varies according to circumstances from 18 to 35. More particularly, special devices are provided, both at the point in which the wet material enters the rotor of the machine and at the point where the material leaves the rotor after the extraction of the liquid it contained.

The wet textile bers introduced into the known machines for being dried', due to their tendency to easily clog, when falling afterwards into the machine in more or less big lumps, and. meeting the spirals of truncated-conical screw place themselves astride the former and piling-up progressively of the said materials will end in obstructing completely the charging mouth.

A certain amount of fibers in the known machines manage to pass into the space between two adjoining spirals of the conical screw, working their way towards the discharge, but, having undergone a certain amount of dehydration, due to the centrifugal action on said fibers, they become lighter and increase considerably in volume and may advance with difliculty, along the incline of the spirals of screw notwithstanding the thrust on them of the centrifugal force and the difference in velocity between the conical basket and the conical screw inside the same. i

Even when a part of dried textile fibers reaches the bottom of the conical screw and discharges from the same, it happens that a substantial part of said fibers fall astride over the arms of the spider carrying the conical basket piling-up more and more so as to prevent satisfactory operation of the apparatus.

Finally a certain amount of fibers manages to leave the machine regularly through a spider and due to the inside structure of the machine, its internal ribs, and its particular shape, it happens that the bers have a tendency to stop and pileup more and more against any projecting part, thus obstructing the machine internally.

rIhe attached drawing shows an embodiment of the improved hydroextractor with which the troubles stated are avoided.

Fig. 1 is a vertical section of the hydroextractor, for treating textile bers natural or articial.

Fig. 2 is a detail shown in section of the conical basket, perforated in its upper part, in which teeth are clearly shown.

Fig. 3 is a detail in section of the basket 3, of the conical inside screw 4 and of the spider 5, in which is clearly shown one of the lower teeth of the spiral of the conical screw.

Fig. 4 is a perspective View of the conical screw provided with a number of spirals having a gradually decreasing slope.

'Ihe truncated-conical basket 3 is provided 'at its top with devices capable of securing a constant and regular self-discharge of the bers which pile-up astride of the spirals of the conical screw 4. These devices which may vary in practice from those described, without however exceeding the limits 0f the invention, can be formed by a number of properly shaped teeth 6 xed inside at the top of the truncated-conical basket 3, so that, due to the difference in speed of the revolving conical basket 3 and of the revolving screw 4, the fibers are gradually wiped away as they fall astride over the screw spirals 4.

The distance between said teeth 6 and the beginning of the spirals of the screw will be varied according to the nature of the fibers to be treated.

The truncated-conical screw 4 is provided with a number of spirals. The angle of the cone varies between 18 and 35, according to the dierent textile bers to be treated, and the slope of the spirals varies relative to the horizontal plane, namely diminishing gradually from top to bottom of the screw 4 as shown in Fig. 4. I

Moreover the spirals of the screw 4 are placed on a conical surface whose conicity relatively to the axis of rotation is greater than that of the conical basket 3. Such an arrangement provides a greater annular space at the mouth at which the fibers are fed to the machine.

A supporting spider 5 is provided for the conical basket 3, with the least possible number of arms so as to reduce to a minimum the number of obstacles on which the dried bers intheir discharge from the conical screw can pile-up on the spider-arms.

As some of the fibers will always manage to place themselves astride `the spider-arms,r the bottom-end of the various spirals of the conical screw 4, carries suitable devices for engaging and discharging the fibers which are stopped by the arms of the spider 5.

Said devices, which can be in practice of a different design, are formed by suitable projections or teeth 1 arranged at the lower end of each spiral-blade of the conical screw 4, which teeth, 4due to the difference in speed existing between said screw 4 andthe conical. basket 3, provide for a constant and effective wiping off of the fibers fallensastride the spider arms 5.

:The distance between said teeth 'I and spiderarms 5 will vary according to the nature of the textile fibers to be treated.

The inside ofthe frame of the machine at the point where thematerial leaves the bottom of the rotor, after having been dried,A is built conical, `with the greatest possible slope. A central housing of the machine, enclosing the mechanical elements of the drive, is supported and rigidly connected withthe frame with the least number of arms orribs, profiled and placed inthe most lsuitable manner, in order to limit the eventual piling-up of textile fibers at said points and, favouring their removal by the Ventilating action dueto the fast rotation of the screw.

More exactly, the constant centrifugal automaticexliauster for natural and artificial textile fibers, 'modified for theV specified purpose, is formed by an outer frame l, having at the top a charging hopper 2, entering into the truncatedconical basket 3 suitably perforated, in which is arranged the truncated-conical screw' 4 provided with a plurality of, spirals.

The conical basket3 is supported by the spider 5iwhich in its turn is mounted on. a hollow spindle, through which passes the solidV shaft'rcarrying the conical screwv 4.Y

By means of special mechanical gears enclosed inthe central vhousing 9 of the machine, both above mentioned spindles are rotated in the same direction but withV a given difference in speed between each other. f

The central housing 9 of the machine, enclosing hermetically the various driving gears of the machine, is rigidly xed to the outer machine frame by means of a few ribs' Ill suitably profiled so asto offer the least possible obstacle to the free fall' of lthe centrifugated material;

The inner profile of the frame I, is conical, with its base turned downwards and made as ample as conveniently possible so as to allow the material discharged from the rotor after having been dried, to drop freelywithout any possibility ofgits being retainedV in any way.

The `wet fibers entering the machine are violently flung against the perforated conical basket 3 thus beginning immediately to lose a part of the liquid in which they are soaked and the slope ofthe conical basket 3 with regard to its axis of rotation being greater than the angle of friction Vof the material itself the bers move downwardly.

As mentioned above, a part of the fibers will manage to pass on freely, within the space between each spiral and the next one on the conical screw, but another part will ride over each of the spirals of said screw, piling-up on the same. i g

As both the conical basket 3 andthe conical screw 4 revolve in the same direction, but with a certain difference in speed, their relative motion is such as may be imagined if the conical screw 4 was motionless with the conical basket 3 revolving around it at the above-mentioned relative speed, which speed can be increased more or less, according to the nature of the textile fibers which undergo centrifugation. It follows that the teeth 6, fixed in the inside of the top of the conical basket 3, will regularly and Vconstantly Wipe awayV during their rotation any fibers which may have piled-up on the different spirals of the conical screw 4, so that the pilingup of materials at the top of the conical basket 3 .is avoided and regular and constant descent of the fibers towards the bottom of the conical basket is secured. Having thus obtained the constant motion ofthe textile fibers, subjected to centrifugal` exhaustion, `along the free spacesexisting between eachpile and th'e next of conical screw 4, it may be noted "at this point that said bers have been. freed of part ofthe liquid of which they were soaked and are' compelled 'to adhere strongly against theinner surface .of the conical basket 3, due tothe centrifugal action to which they are subjected. At this, point, due to the rotation of the basket and to the'component ofthe centrifugal'force along the slope 0f the basket actingV on theiibers, there will be automatically a regular and Aconstant motion of descent of said fibers towards the bottom of the conical 'basket 3,-until the same fibers Will discharge through the arms of the spider 5,'supporting the conical basket 3, after complete exhaustion of the liquidthey contained.

If someV of the-fibers engage and pile up on the` spider arms 5'these fibers will-b`e removed by the teeth 1 thus securingthe regular and constant release of all the dried fibers towards the discharge of the machine.

The shape and thedistance of the' teeth?, mentioned above, relatively to the armsof spider 5, will be such as to avoid in any casethe fibers being torn, the same being simply wiped olf and left to drop freely.

The fibers, during their treatment through the machine, will be compelled to descend regularly and constantly along thervariably sloped mul- ,tiplespiralsof the conical screw'4, within a certain time, which is a function of thev pitch of the spiral of screw4` and of the :difference in rotary speed ofthe same from that of the conical basket 3. i f

The fibers, while descending along the spirals of the conical screw 4, are subject to a centrifugal force increasing constantly with the diameter of the conical basket 3, which securesa perfect dry ing of said bers. Y Y

The liquid exhausted from the fibers is collected in a circular collector 8, surrounding the perforated conical basket 3 and is discharged through any lateral pipe, and the dried material drops at the bottom of the machine, where it can be collected in any known manner, for further processing. l

It is understood that details of design and in shape may Vary from those speciiied and illustrated, without thereby exceeding the limits of the invention.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In a centrifugal dehydrator for textile fibers of the type including a truncated conical basket member, a truncated conical screw member disposed within said basket, means for rotating both of said members in the same direction but at different speeds relativelyr to one another, an inlet for textile iibers in one end of said basket, and an outlet for dehydrated fibers in the other end of said basket, a plurality of varying spiral means on the periphery of said truncated conical screw member, the slope defined by said spiral means gradually decreasing from the top of said screw member adjacent said inlet to the bottom of said member, whereby the textile fibers introduced in said inlet are first drawn downwardly and gradually outwardly in sliding engagement with the inner surface of said basket.

2. A centrifugal dehydrator for textile fibers, comprising a truncated conical member, spiral means on the periphery of said member, a truncated conical perforated basket surrounding said member, an inlet for introducing textile fibers into one end of said basket onto said conical member, an outlet for dehydrated iibers in the other end of said basket, arms adjacent said outlet supporting said basket, means for rotating said member and said basket in one direction but at different speeds relatively to one another, depending teeth carried by said basket adjacent said inlet cooperating with said spiral means, and teeth carried by said member terminating adjacent said arms, whereby during rotation of said basket and said member, textile fibers lodged on said spiral means adjacent said inlet and on said arms adjacent said outlet are continuously removed by said teeth.

3. A centrifugal dehydrator for textile fibers comprising a truncated conical member, spiral means on the periphery of said member, a truncated conical perforated basket surrounding said member, an inlet for introducing textile bers into one end of said basket, means for rotating said member and said basket in one direction but at different speeds relatively to one another, depending teeth carried by said basket adjacent said inlet, terminating adjacent said spiral means, whereby during rotation of said basket and said conical member, textile fibers lodged on the upper edge of said spiral means Will be engaged by said teeth and removed, and an outlet for dehydrated iibers on the opposite end of said basket.

4. A centrifugal dehydrator for textile iibers comprising a truncated conical member, spiral means on the periphery of said member, a truncated conical perforated basket surrounding said member, an inlet in one end of said basket for introducing textile fibers therein, an outlet for dehydrated bers in the other end of said basket, arms supporting said basket adjacent said outlet, means for rotating said conical member and said basket supporting arms in one direction but at diierent speeds relatively to one another, and teeth carried by said member adjacent said outlet and terminating adjacent said basket supporting arms, whereby during rotation of the latter and said conical member, textile iibers lodged on said supporting arms will be removed by said teeth.

`ALDO CASAGRANDE, 

